I would just leave all of your BIOS options at their default settings!
1. Overclocking should not be dabbled with if you have no idea what it entails. Essentially, in this case, you are making the CPU run at a speed it was not rated to run at. Heat output will increase, and the lifetime of the component will decrease. I wouldn't worry about it, since your CPU is still pretty quick.
Leave the AGP speed at 66Mhz - any higher and you may experience instability.
2. Your components may not be able to handle "top performance" mode. This could entail more agressive memory timings among other things, which may result in system instability if your memory is unable to handle the new settings. Leave it as it is for the moment - I don't think it will make much of a difference.
3. Default settings.
4. USB Keyboard and mouse support can be enabled if you have a USB keyboard and mouse and wish to use them outside of Windows. Enabling them regardless will have no effect on your system. Leave everything else at default.